The use of zeolites as catalysts and/or catalyst carriers has long been recognized and many methods to improve zeolitic base materials have been reported in the art. In zeolite research and development much attention has been devoted to physically changing the nature and possibly the properties of zeolite base materials, e.g. by calcining, calcining under so-called self-steaming conditions or by wet calcination. Also the treatment with ammonium-ions in various stages of the zeolite preparation procedures has been reported. It has also been reported that zeolites can be modified by treating them with certain metal salt solutions in combination with various pre- and after-treatments to ensure that the zeolites are produced in the most active form. In this respect reference is made to U.S. Pat. No. 4,415,519 issued Nov. 15, 1983, describing a zeolite modification in which a sodium-type Y zeolite is exchanged with the ammonium salt solution, the ammonium exchanged zeolite is calcined, e.g. in a self-steaming condition, and the calcined product is reacted with an acidic aluminum salt solution. Subsequently, the aluminum-exchanged zeolite is again subjected to ammonium-change.
It has been found that zeolitic catalysts with interesting properties can be produced by ion-exchange of low alkali oxide-containing zeolites with certain metal salts, and subsequently, without a calcination treatment, combining the ion-exchanged zeolites with a hydrogenation component of a Group VIII metal and/or a Group VI(b) metal. The catalysts thus prepared are of importance as hydrocracking catalysts.